This invention relates to the optical coupling of light emitted, absorbed or altered by optoelectronic devices, such as photodetectors, light emitting diodes, lasers, vertical cavity surface emitting lasers (VCSEL), etc., with optical waveguides, such as optical fibers, planar waveguides, etc., which can be further coupled to standard optical connector types such as the MPO/MTP™ connector.
An optoelectronic chip, containing a device such as a VCSEL, is typically mounted in an electronic package where the direction of the light from the VCSEL is perpendicular (normal) to the surface of both the chip itself and the surface on which the electronic package has been placed. Electronic packages are typically placed on large 2-D flat printed circuit boards (PCBs), and these PCBs are typically stacked within a chassis with very narrow gaps between the PCBs. This type of structure requires that all the connections to and from the PCB enters and leaves from the PCB's edge, called the card-edge. Since the light from the VCSEL is emitted perpendicular to the PCB, a method would be desirable to direct the light off the edge of the PCB, and hence parallel to the flat surface of the PCB. The typical method used to achieve card-edge connections with light is to use a flexible-PCB bent at 90-degrees where one face of the flexible-PCB connects to the main PCB and the other face has the optoelectronic chip where the light from the VCSEL is directed parallel to the surface of the main PCB. The light is then butt-coupled into an optical fiber.
The bevel coupling method allows the optoelectronic chip to be placed in the conventional packages where the light is directed perpendicular to the PCB. The optical fiber is then beveled at 45-degrees and placed over the light beam such that the light is reflected at 90-degrees and propagates parallel to the PCB within the optical fiber. This method allows more conventional packaging and reduces the alignment tolerance because the length of the optical fiber is essentially laid over the flat surface of the PCB.
The method of embedding optical fibers in a block (primarily a silicon v-groove sandwich using two silicon chips to sandwich the optical fibers) to precisely hold optical fibers is very well known in the literature. Furthermore, the beveling of this block at a given angle (primarily at 45-degrees) to reflect light sideways out of the embedded optical fibers is also very well known in the literature. This is discussed in numerous prior-art patents, such as U.S. Pat. No. 4,900,118 granted Feb. 13, 1990, U.S. Pat. No. 6,004,042 granted Dec. 21, 1999, as well as most of the cited references in these two US Patent Documents.